Wrist Flexors: Functional Anatomy Guide

The wrist flexors refer to six muscles in the anterior compartment of the forearm that act on the wrist and finger joints.

Wrist Flexors

As a group, the primary action of the wrist flexors is, you guessed it… wrist flexion! As I’ll detail later, these muscles are also responsible for other movements of the fingers and wrist.

Each of the muscles is listed below:

  • Flexor Carpi Radialis (FCR)
  • Palmaris Longus (PL)
  • Flexor Carpi Ulnaris (FCU)
  • Flexor Digitorum Superficialis (FDS)
  • Flexor Digitorum Profundus (FDP)
  • Flexor Pollicis Longus (FPL)

While all the wrist flexors are in the anterior compartment of the forearm, they can be divided into three sub-categories based on the relative depth of the muscles:

  • Superficial Anterior Compartment of the Forearm: The layer of muscle closest to the surface; includes the FCR, PL and FCU (and the pronator teres)
  • Intermediate Anterior Compartment of the Forearm: The middle layer of muscle; includes the FDS
  • Deep Anterior Compartment of the Forearm: The layer of muscle furthest from the surface; includes the FDP and FPL (and the pronator quadratus)

The majority of the points of origin for the wrist flexors are somewhere on the medial surface of the distal humerus or the anterior surfaces of the ulna and radius.

From their origin attachments, the wrist flexors move in a distal direction, down the front of the forearm, and insert on the anterior surfaces of the carpals, metacarpals and phalanges.

The FCR, PL and FCU have a parallel fiber orientation and fusiform muscle architecture. The FDS, FDP and FPL have an oblique fiber orientation and unipennate muscle architecture.

Note: Although most sources I found described the FCR and FCU fusiform, this source classifies them muscles as bipennate muscles.

Also Called

  • Front of the forearm
  • Flexor muscles of the forearm
  • Finger flexors

Origin, Insertion, Action & Nerve Supply

Muscle Origin Insertion Action Nerve Supply
Flexor Carpi Radialis (FCR) Medial epicondyle of humerus via the common flexor tendon Base of 2nd metacarpal
  • Wrist flexion
  • Wrist abduction
Median nerve (C6-C7)
Palmaris Longus (PL) Distal half of flexor retinaculum and apex of palmar aponeurosis
  • Wrist flexion
  • Tenses palmar aponeurosis
Median nerve (C7-C8)
Flexor Carpi Ulnaris (FCU)
Humeral Head
Pisiform, hook of hamate, 5th metacarpal
  • Wrist flexion
  • Wrist adduction
Ulnar nerve (C7-C8)
Flexor Carpi Ulnaris (FCU)
Ulnar Head
Olecranon process and posterior border of ulna (via aponeurosis)
Flexor Digitorum Superficialis (FDS)
Humeroulnar Head
Medial epicondyle of the humerus via the common flexor tendon and the coronoid process Shafts of middle phalanges of medial four digits
  • Flexion of the index, middle, ring and little fingers at proximal interphalangeal and metacarpophalangeal joints
  • Wrist flexion
Median nerve (C7-T1)
Flexor Digitorum Superficialis (FDS)
Radial Head
Superior half of the anterior border of radius
Flexor Digitorum Profundus (FDP) Medial Part Proximal three quarters of medial and anterior surfaces of ulna and interosseous membrane Bases of distal phalanges of 4th and 5th digits
  • Flexion of the ring and little fingers at distal interphalangeal, proximal interphalangeal and metacarpophalangeal joints
  • Wrist flexion
Median nerve (C7-C8)
Flexor Digitorum Profundus (FDP) Lateral Part Bases of distal phalanges of 2nd and 3rd digits
  • Flexion of the index and middle fingers at distal interphalangeal, proximal interphalangeal and metacarpophalangeal joints
  • Wrist flexion
Anterior interosseous branch of median nerve (C8-T1)
Flexor Pollicis Longus (FPL) Anterior surface of radius and adjacent interosseous membrane Base of distal phalanx of thumb Thumb flexion at interphalangeal and metacarpophalangeal and carpometacarpal joints

Exercises:

Note: In the table below, I have only included exercises that directly target the wrist flexors.

That said, there many other exercises that work the wrist flexors significantly but indirectly. This includes any heavy exercise where you are gripping the bar or dumbbells directly against gravity (i.e. any deadlift, shrug, dumbbell lunge, pull up or row variations with heavy enough weight).

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Other:
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Weighted:
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Bodyweight:
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Isometric:
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Stretches & Myofascial Release Techniques:

Stretches

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Self Myofascial Release Techniques

When using these techniques, give special attention to the common trigger points shown in the image below.

wrist flexor trigger points

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Common Issues:

  • Overactive/Short Wrist Flexors: The wrist flexors are prone to becoming overactive and short from overuse in repetitive activities involving wrist flexion, gripping or forearm pronation. Such activities are often athletics-related: any overhand throwing activity, golf swing, bowling, tennis forehand stroke, gripping a rock climbing hold or gripping a bar during weight training. The overactive these muscles become, the more tension they put on the common flexor tendon.
  • Medial Epicondylitis: Medial epicondylitis, better known as golfer’s elbow, will develop if the common flexor tendon is put under too much stress from overuse and wrist flexor/pronator tightness. The excessive stress leads to chronic degeneration of the tendon and pain on the medial epicondyle. The pain is most intense during wrist flexion, forearm pronation, passive wrist extension, passive forearm supination and gripping activities. Other symptoms include reduced grip strength, in addition to weakness and limited range of motion during wrist flexion and forearm pronation.

Training Notes:

  1. If you have overactive and short wrist flexors, do the following:
    • If possible, cut down on any repetitive daily or work activities involving the wrist flexors or pronator teres. This includes anything that requires gripping, rotating your forearm or flexing your wrist (e.g. using most hand tools: hammer, screwdriver, hand saw, chain saw, garden tools, etc.).
    • Reduce training volume on wrist flexor exercises. However, you don’t need to stop all exercises, since performing some high rep wrist flexor exercises can help prevent medial epicondylitis, especially if you include eccentric exercises.
    • If you are doing any wrist flexor training, use light weight and higher reps. Going too heavy can put excess strain on the tendon.
    • Do wrist flexor releases and stretches on a daily basis, and before any workouts that requiring wrist extension flexibility (i.e. workouts with front squatspower cleans or other Olympic-style lifts, push ups, overhead press, etc.) or workouts involving a lot of gripping (i.e. biceps and back training). Also, stretch/release them before and after doing any wrist flexor/extensor workouts.
    • Chances are your wrist extensors are inhibited/lengthened compared to your wrist flexors. If this is the case, you need to start training your wrist extensors more than your wrist flexors.
    • If you have medial epicondylitis, see how to treat golfer’s elbow (article coming soon).
  2. If your wrist flexors are healthy and your main goal is to get them bigger, then the following advice is for you:
    • If you haven’t started doing any direct wrist flexor exercises, then that’s your first step. Pick 1-2 wrist flexor exercises to start out with. I personally recommend dumbbell wrist curls and wrist roller flexions.
    • The wrist flexors consist of a high percentage of slow-twitch muscle fibers. That is, they’re endurance muscles, which contract slowly (i.e. non-explosively) and are highly resistant to fatigue. In order to get them to grow, you need to train with high reps/volume/frequency. To start with, train them twice a week for 6-8 sets of 12-20+ slow and controlled (2-3 secs) reps. If your forearms aren’t burning and pumped full of blood after each set, you’re doing it wrong!
    • Do wrist flexor training toward the end of your workout so you don’t interfere with major lifts that require full grip strength (e.g. deadlift, row, bench press).
    • Implement the above guidelines for 2+ months and monitor your progress. Don’t change anything until your progress slows considerably or stops altogether, at which point you can increase training volume by 2-4 more sets per workout, and/or increase training frequency from twice weekly to three times per week.
    • Be sure to also train your brachioradialis and wrist extensors to improve your overall forearm muscular development:
      • Wrist extensors: Train the wrist extensors using the same high rep/volume/frequency protocol that is outlined above for the wrist flexors. Also, train your wrist flexors and extensors in the same workout.
      • Brachioradialis: Unlike the wrist flexors and extensors, the brachioradialis is a fast-twitch muscle. It generally responds better to heavier weight and fewer reps/less volume and low to moderate training frequency. For brachioradialis exercises such as the hammer curl, I suggest starting with 3-4 sets of 6-10 reps, 1-2 times per week. Train the brachioradialis when you do biceps exercises. If possible, also include your wrist flexor and extensor exercises in the same workout, but after training the brachioradialis.
    • If you’re training the wrist flexors directly, stretch and release them before and after workouts to prevent imbalances or tendon issues from developing. Include stretch/release techniques as needed on days when you don’t train them. If you feel like you might be overworking your wrist flexors and putting to much stress on the tendon, then reduce your training volume and frequency immediately.

About the Author Alex

Hey! My name is Alex, and I'm the owner and author of King of the Gym. I started this website back in late 2009 during college, and it has been my pet project ever since. My goal is to help you learn proper weight training and nutrition principles so that you can get strong and build the physique of your dreams!

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